Subaru 2002 IMPREZA Service Manual page 597

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
23 GROUP OF #3 AND #4 CYLINDERS
24 GROUP OF #1 AND #3 CYLINDERS
25 GROUP OF #2 AND #4 CYLINDERS
26 CYLINDER AT RANDOM
Check
Are there faults in #3 and #4
cylinders?
Are there faults in #1 and #3
cylinders?
Are there faults in #2 and #4
cylinders?
Is the engine idle rough?
EN-165
ENGINE (DIAGNOSTICS)
Yes
Repair or replace Go to DTC P0170.
the faulty parts. <Ref. to EN-156,
DTC P0170 —
NOTE:
FUEL TRIM MAL-
• Check the fol-
FUNCTION —,
lowing items.
Diagnostic Proce-
• Spark plugs
dure with Diagnos-
• Fuel injectors
tic Trouble Code
• Ignition coil
(DTC).>
• If no abnormal is
discovered, check
for "16. D: IGNI-
TION CONTROL
SYSTEM" of #3
and #4 cylinders
side. <Ref. to EN-
72, IGNITION
CONTROL SYS-
TEM, Diagnostics
for Engine Start-
ing Failure.>
Repair or replace Go to DTC P0170.
the faulty parts. <Ref. to EN-156,
DTC P0170 —
NOTE:
FUEL TRIM MAL-
Check the follow-
FUNCTION —,
ing items.
Diagnostic Proce-
• Spark plugs
dure with Diagnos-
• Fuel injectors
tic Trouble Code
• Skipping timing
(DTC).>
belt teeth
Repair or replace Go to DTC P0170.
the faulty parts. <Ref. to EN-156,
DTC P0170 —
NOTE:
FUEL TRIM MAL-
Check the follow-
FUNCTION —,
ing items.
Diagnostic Proce-
• Spark plugs
dure with Diagnos-
• Fuel injectors
tic Trouble Code
• Compression
(DTC).>
ratio
• Skipping timing
belt teeth
Go to DTC P0170. Repair or replace
<Ref. to EN-156, the faulty parts.
DTC P0170 —
NOTE:
FUEL TRIM MAL-
Check the follow-
FUNCTION —,
ing items.
Diagnostic Proce-
• Spark plugs
dure with Diagnos-
• Fuel injectors
tic Trouble Code
• Compression
(DTC).>
ratio
No